Another way to look at this... We hold electronic equipment manufactures responsible for making stuff that doesn't wipe out the spectrum, do we not? Lights, TVs, wall warts, etc. Shouldn't our own equipment do the same? Really, it should be held to a higher standard, IMHO. if we expect our neighbors TV to be RF quiet and not to cause us heartache, we CERTAINLY should expect that our fellow ham isn't causing the same problem. We can't just gloss over stuff like this and expect that we can cry foul when a LED light fixture makes 20M unusable, but not hold ham equipment manufacturers accountable as well. Not exactly "apples to apples", but we should be vigilant to equipment contributing to the noise problem, especially when it's "our" equipment. Just my opinion. Steve KV6O
Hi Derek, Glad you found out the same things I did with your 891 vs the Icom 7300. They have lowered the price now to $630.00 now until th end of August. That is a steal when you consider the features built into the radio. It truly is a FTDX 1200 in a small box. Thanks for the nice article. 73, KO4CH Jerry Koch
Steve, I agree 100% - but there's more! Others can claim ignorance - that they "didn't know their products could interfere with hams". Heck, some will claim they didn't even know we exist! We cannot claim such ignorance. As licensees, we're supposed to know basic stuff like this. My guess is they lowered the price because they know of the problems and want to get rid of the inventory before word gets out. 73 de Jim, N2EY
Hi Jim, Another problem with apocryphal "didn't cause a problem for FD this year" is that there are so many variables here it's hard to use those reports as an indication that nothing is wrong. For example: What was the exact separation of TX and RX frequencies? TX phase noise falls off with separation in frequency as well (e.g. 100 kHz separation is quite a bit better), so without knowing that, you don't know whether it was causing problems or not. For a TX next to a RX, were you in the near or far field? That could have a large impact if you happen to be in a null in the near field, whereas you would still be causing problems to people in the far field. At 40 meters, a half-wave RX dipole is in the TX near field out to almost 19 meters (nearly 60 feet) assuming a dipole as well for TX . Even in the far field, higher gain HF antennas might also make the problem better even if the RX were in the near field, depending on whether the RX antenna was in a mutual null. On the other hand, phase noise test equipment gives a precise answer on how much TX near-in hash is being generated. Beyond that, it's basic EM propagation theory. I'm a bit mystified if the apocryphal reports are really inferring that the test measurements are not correct (Bob Allison knows what he is doing). 73 de Phil, W1PJE
Agreed. If the 'phone station is up around 3950 and the digital station down at 3580, it's a very different world from being 5 kHz away. All sorts of possibilities. For example, if Station A is on 40 and Station B is on 20, B may hear A's second harmonic - but the opposite won't happen. If a Station B is using an antenna that has some "selectivity" - say, a 20 meter monoband Yagi - the amount of RF picked up from Station C (on 75 meters) will be much less than if an "unselective" antenna were used (say, a trap vertical that covers several bands, including Station C's). All true. There's also the question of "how does a particular rig behave when faced with an enormous off-channel signal?" Will the overall gain go down? Will the apparent noise floor rise? Will their be "signals that aren't really there" created? Will the poor thing just fold up and go quiet? Do these effects happen gradually or suddenly? IIRC, the IC-7300 actually indicates overload - and when it happens, the poor thing just folds up, because the A/D converter just can't deal with the situation. That's a different behavior from many "analog" rigs. 73 de Jim, N2EY
I can't seem to find it using my Google-fu right now, but someone wrote an article on the current crop of transceivers a few years ago, and the transmitted phase noise - a ranking, if you will. Bob Allison's statement , "highest they've ever seen", sounds bad, but if it's 0.5 dB worse than 10 other rigs out there then that's not really an issue. If it's 10dB worse... different story. It would be nice to have this data, much like we have Sherwood for receiver performance, so that hams looking for a new rig can be better informed. Steve KV6O
Thank-you. Real-world information, and not armchair musings from people who have no experience with the radio. If this radio were truly interfering with other radios a mile away, as has been suggested by people who don't own it, and appear to be more interested in re-writing the AARL test results, then I doubt we would have seen it on the market. This is an AARL-tested, and FCC-approved radio. It's not a chinese laser Christmas light import. Some of this apocryphal chatter is plain silly.
It's not usable real world info, though. What band(s) was the FT-891 transmitting on? What band(s) was the other station listening to? What antennas were in use? What was the other station's rig? Were there external band filters in use? Stubs? Preamp on or off? Attenuator on or off? The criticism of the FT-891 is about close in TX phase noise. Not adjacent-band spurs. BIG difference!
I said nothing about band spurs or close-in phase noise. I understand that the FT-891 is guilty until proven innocent. All by people who do not own the radio, or even have a chance to test it in the field, with other radios. I get it.
So I can summarize my response and that of N2EY: Several here appear to have a fundamental difference between the weight they give to a test where one rigorously defines the independent and dependent variables, and where one does not. Ultimately, it's up to the individual to gauge whether or not they care because, as you correctly point out, this rig passed the regulatory hurdles. Look at the numbers, do the calculations, and come to your own conclusions. But it seems a stretch to assume that the FCC and ARRL testing covers all possible problems that might be created in a crowded HF environment. They do not, in particular for close-in phase noise as has been repeatedly stated. That's borne out by the math. If one argues that this math is somehow flawed, you've got quite an uphill climb ahead of you to make that case. I am mystified though - why reach for the ad hominem, as in "armchair"?
No, you don't get it. The ARRL Product Report specifically mentions the TX phase noise issue. ARRL does not "approve" rigs, they just test them. FCC's certification process doesn't include things like transmitted phase noise unless it's REALLY bad. Phase noise a few kHz, or a few dozen kHz, from the transmitting frequency is a whole different thing from noise and spurs on an adjacent band. I've done more than 50 Field Days, with a wide variety of rigs. Dealt with a wide variety of problems and situations. How many Field Days have you done?
One more thing: you state "more interested in re-writing the AARL test results". But the phase noise value I quote is directly from the ARRL test results. How is that "rewriting"?
Simple... Test it, and provide results. The "arm chair" comment is entirely accurate, until an engineer sits down and tests it. Period. I have quoted links to two tests of the FT-891 already, but they are not good enough, because some would rather muse about hypotheticals without actually testing those hypotheticals. Simple answer to those people: test it at a field day, and get back to us. And please document your results fully.
Ok. How many field days have you done with the FT-891? You sound like a good candidate for a test. Please document your results. It would be nice to see some more results. The radioficion link I posted in the ad went into some detail, and although his English was poor, he claimed it was much ado about nothing. Next question... have any of your 50 field days involved the FT-857, or the IC-735? How did those radios perform, in terms of creating phase noise issues?
Your test is invalid because a Field Day has so many uncontrolled variables that a controlled test is not possible under those conditions. Rather, a lab bench test removing the effects of antenna mismatch, antenna gain, far/near field, TX power fluctuation, etc. would be more informative. This would best be done with Bob Allison at ARRL Labs, given the pedigree of the original information. I'll ping him and see what can be done for a controlled test. Perhaps it would be a worthwhile illustration for QST to highlight the TX phase noise problem. Good suggestion. Who knows, we might discover that the TX phase noise concept is flawed somehow, and learning that would be a scientific advance worthy of the work since it would violate the huge body of literature about Allan variance, oscillator nonlinear behavior, Gaussian random statistics, and other well tested models of the real world. In the meantime, perhaps others can also do this testing themselves. Some of the difficulty here is that one needs to benchmark the actual set's phase noise performance before testing, and a good phase noise test set requires a reference better than the oscillator you are trying to test. This gets expensive in a hurry, which is why it's a good idea to coordinate with a lab known to have ultrastable TCXOs or better yet cesium/rubidium or hydrogen masers as a reference. Hmm, I might know just such a place...
